The Characteristics Analysis Of TCIPC And The Influence Of Its Transient Process In Parallel With MOV

Flexible AC Transmission System is a series of flow control devices which isbased on automatic control and power electronics. In recent years Interphase PowerController(IPC) as one of the products of FACTS receives more attention, due to itspower flow control characteristic, fault current limitation and decoupting of theinterconnected network.As the parameters of IPC which are constituted by conventional elements adjustthe speed relatively slowly, in order to improve the adjusting speed of IPC andimprove its operating characteristics, the conventional IPC conduct electronictransformation to be thyristor controlled Interphase Power Controller (TCIPC). In thispaper, base on the basic structure of interphase power controller， and expound thebasic principle of TCIPC power flow control with the foundation of TCIPC model.On the one hand, analyze the characteristics of TCIPC flow control and limit theshort-circuit current and voltage decoupling. On the other hand, discuss the cause ofover-voltage during the process of IPC power flow control. The simulations analyzethe issues, which include that the parameters of IPC are adjusted beyond the certainscope in normal operation that causes the over-voltage, and the resonanceover-voltage generated by IPC port opening.In two ends of the branch of TCIPC that is in parallel with metal oxide varistor,which could protect IPC when it may cause the over-voltage in operation, but theaccess of MOV has the effects on the transient process of running state change. Thispaper studies the dynamic model of TCIPC in parallel with MOV based on the basicstructure of TCIPC, analyzes the influence that is in parallel with MOV has on thetransient transition process of TCIPC when the operation mode changes. And takingthe power as the reference, design closed-loop PI given impedance controller. As anexample of the weak equivalent of two grid system with TCIPC for simulationanalysis, the results are obtained: the presence of MOV makes the power flow control ability drop, and prolongs the transient transition time to restore stability.The interconnection between power system and thyristor controlled InterphasePower Controller(TCIPC)could not only regulate the power flow, but also has certaininfluence on the stability. This paper could analyze the mechanism of improvingpower system transient stability with regulating IPC parameters through power anglecurve of a simple system, and make the expected value of the line current and activepower as the reference signal of controller, designs a fuzzy PID self-tuningimpedance control model. Simulation results verify TCIPC uses the control systemcan improve the stability of the system, and reduce the influence of MOV.